[Imaging analysis of ameloblastoma, odontogenic keratocyst and dentigerous cyst in the maxilla using spiral CT and cone beam CT]

Objective: To analyze the radiolographic features of ameloblastoma (AM), odontogenic keratocyst (OKC) and dentigerous cyst (DC) in the maxilla by spiral CT (SCT) and cone-beam CT (CBCT), and to provide useful information for the differential diagnosis of benign radiolucent lesions in the maxilla. Methods: Clinical records, histopathological reports and SCT or CBCT imaging of 85 patients with primary maxillary AM, OKC or DC admitted to Peking University School and Hospital of Stomatology from December 2012 to May 2017 were collected. Radiographic characteristics including site, size, shape, cortex expansion, internal structure and effects on neighboring tissue were analyzed. For OKC and DC, the relationship between cysts and enveloped teeth was classified as centripetal, eccentric and adherent. Results: The 85 patients included 56 males and 29 females, aged from 8 to 84 years old. Eighty-three patients had a single lesion, whereas 2 patients had bilateral cysts. In total, 87 lesions were analyzed, comprising 22 AM, 45 OKC and 20 DC. Among the 22 AM, 11 lesions were desmoplastic type, 16 were round-like in shape and 18 presented with buccal expansion. The shapes of the 45 OKC varied as round-like (n=26), oval (n=3), reniform (n=4), sinus-like (n=5), sinus+round (n=5) and irregular (n=2). Furthermore, 30 OKC presented with buccal expansion, 22 nearly filled the maxillary sinus and 26 were 'dentigerous'. The tooth-cyst relationship of the 'dentigerous' OKC was centripetal in 11, eccentric in 4 and adherent in 11. Among the 20 unicystic DC, 8 lesions were centripetal, 6 were eccentric and 6 were adherent type; 16 DC presented with buccal expansion. Conclusions: Demosplastic type is common in maxillary AM. Most AM are round-like in shape and expand buccally. The shape of maxillary OKC varies greatly and maxillary sinus filling is common. More than a half of OKC appear 'dentigerous'. For DC and OKC, tooth-cyst relationship can be centripetal, eccentric and adherent.